Permanment heat activated electrographic printing process and composition

ABSTRACT

An image is printed on a medium by means of an electrographic device using an ink composition comprising heat activated inks, without substantial activation of the inks during the process of printing the image onto the medium. A molecular sieve added to the ink composition assists activation control. The image is transferred from the medium to the object on which the image is to permanently appear by applying sufficient heat and pressure to the medium to activate and permanently transfer the inks from the medium to an object.

This application is a continuation in part of application Ser. No.08/299,736, filed Sep. 1, 1994, now U.S. Pat. No. 5,488,987, which is acontinuation in part of application Ser. No. 08/195,851, filed Feb. 10,1994, now U.S. Pat. No. 5,431,501, which is a continuation in part ofapplication Ser. No. 07/724,610, filed Jul. 2, 1991 U.S. Pat. No.5,302,223, which is a continuation in part of application Ser. No.07/549,600, filed Jul. 9, 1990, now abandoned.

FIELD OF THE INVENTION

This invention relates to printing generally, and is more specificallydirected to a method of printing heat activated inks by means of anelectrographic device onto paper or other printable substrate as amedium, and subsequently heat activating the ink, thereby transferringthe design formed by the ink from the medium to a second substrate onwhich the design is to permanently appear.

BACKGROUND OF THE INVENTION

Words and designs are frequently printed onto clothing, other textilematerials, and other objects. Common means of applying such designs toobjects include the use of silk screens, and mechanically bonded thermaltransfers.

The use of computer technology allows substantially instantaneousprinting of images. For example, video cameras or scanning may be usedto capture an image and input the image into a computer. The image maythen be printed from the computer by any suitable printing means,including mechanical thermal printers, ink jet printers and laserprinters. These printers will print in multiple colors.

Color electrographic devices, such as laser printers and photocopiers,are in common use. These devices use combinations of cyan, yellow andmagenta inks or dyes to produce multi-color images. These devices useinks in the form of dry toners or developers. These devices incorporatemeans for fusing the printed ink or dye to the substrate, which isusually paper. The fusing means incorporates heat, or heat and pressure.

Sublimation inks have been used with laser printers and copiers toproduce color images on the receptor sheet printed by the printer orcopier, whereby sublimation or activation of the ink or dye occurs atthe time of printing or fusing of the image onto the receptor by theprinter or copier. The sublimation dyes used are low energy, that is,they require low amounts of heat to activate, so that activation isachieved during the very short image fixing time provided byconventional laser printers and copiers. The receptor must be coated, orotherwise include, a polymer or polyester component. Toners comprisingsublimable dyes and a polyester core which are encapsulated in a waxycompound to improve storage stability are disclosed in Japaneseapplication serial number 85-171830.

Sublimation inks have been printed by electrographic devices in theprior art in monochromatic form, without activating the inks as they areprinted onto the substrate. Multiple colors are printed by suchprocesses by multiple apllications of monochromatic process. Theseprocesses are not full process color which can be used with color laserprinters, color copiers or other full color electrographic process. Theprior art has encountered problems related to dye layer build up,registration, and color contamination in trying to print sublimationinks in a non-activated form from known color electrographic devices.

Heat activated transfer inks, such as sublimation inks, change to a gasupon the apllication of heat, and have a high affinity for polyester atthe activation temperature and a limited affinity for most othermaterials. Once the gassification bonding takes place, the ink ispermanently printed, and is highly resistant to change or fading causedby environmental exposure, such as to light, or exposure to certaincommon chemical processes, such as cleaners or laundry products.

Hale, U.S. Pat. Nos. 5,246,518, 5,248,363 and 5,302,223, disclose theuse of thermal printers to produce an image on a medium or transfersheet wherein the image is comprised of sublimation or other heatactivated inks. The method described in Hale does not activate the inkduring the printing of the medium or transfer sheet.

The process of printing heat sensitive or activated inks such assublimation inks by means of a laser printer is similar to the processdescribed in Hale, U.S. Pat. Nos. 5,246,518, 5,248,363 and 5,302,223.The use of heat by electrographic devices such as laser printers andphotocopiers presents the problem recognized in the Hale patents ofprinting heat activated inks in a non activated form by means of suchdevicess. Laser printers and photocopiers in common use employrelatively high temperature fuser devices to thermally fuse or bind theink to the substrate, since these devices anticipate that the image willbe permanently bonded to the substrate which is printed by the device,and do not anticipate a subsequent thermal transfer of the printed imagefrom the substrate.

SUMMARY OF THE PRESENT INVENTION

The present invention is a method of printing heat activated inks ordyes in a non activated form onto a medium in a desired image by meansof an laser printer, for subsequent transfer of the image from themedium by heat activation of the inks. The invention includes ink or dyecompositions comprising heat activated inks or dyes for use with themethod.

The inks are printed in the desired design by means of an electrographicdevice onto a substrate, which acts as a medium. The substrate may bepaper, or it may be other material which is printable by theelectrographic process used by conventional laser printers and copiers.

Electrographic devices incorporate a thermal process, but the heatactivated inks or dyes of the invention are not substantially activatedat the operational temperatures of the device. Heat activation of theinks does not take place at the time of printing of the image by theprinter or copier, but rather, takes place at the time of the transferof the image from the medium to the substrate on which the image ispermanently applied. The non activated inks produce a printed image onthe medium which is recognizable, but the colors are dull and are notacceptable for most applications.

To prevent substantial sublimation of the heat activated inks or dyesduring the thermal process of printing by the laser printer or copier, amolecular sieve is incorporated into the dry toner which comprises thedye. The molecular sieve material entraps the dye or ink molecules andhelps to prevent sublimation of a substantial portion of the dyemolecules at the temperatures at which the laser printer or copieroperates. After the image is printed onto the substrate medium by theelectrographic device, sufficient heat is applied to the substrate totransfer the image from the medium to the second substrate on which theimage is to permanently appear. The application of sufficient heatactivates, or sublimates, the inks during this transfer from the mediumto the substrate. The image is then permanently bonded to the substrate.The permanent image is sharp, with vivid colors forming the image.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the printing process.

FIG. 2 illustrates an example of a design printed by a printer using theprinting process.

FIG. 3 is a diagrammatic illustration showing exemplary elements ofcomputer and printing systems which could be used to achieve theprinting process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the preferred embodiment, a video camera or scanning device 2 is usedto capture an image 3. The image is then input into a computer 4. Thecomputer directs an electrographic device such as a laser printer 6 orphoto copier to print the image. Any means of forming an image which maybe printed from a computer may be used, including images generated bysoftware. Available computer design graphic software may be used, orstill photography may be used. The design may be photographic, graphicartistic, or simply letters or words. The use of cyan, yellow andmagenta ink compositions allow the printer to print in full color ormulti-color designs.

In the present invention, heat activated inks or dyes are used, and aretransferred to a medium by the electrographic device without activatingthe inks. The heat activated inks are transferred onto the medium by theprinter.

Virtually any material which can be printed upon by a conventionalelectrographic device, such as a laser printer or photo copier, andwhich will withstand the transfer temperature of approximately 330°-400°F., as described herein, may be used as a medium. This medium may be anypaper commonly used with color laser printers or copiers, however,standard bond paper may be used, or even a sheet of metal, if the metalcan be handled by the printer. The exception is receiver substrateshaving a high content of polyester or EVA on the surface.

Once the image is printed onto the medium, the image may be immediatelyand permanently transferred onto the substrate, or the image may betransferred from the medium to the substrate at a later time. The designmay be transferred onto a textile substrate, such as a shirt 8, or ontoother substrates, such as metal, ceramic, wood, or plastic. The design3, which is printed onto the medium without substantially activating theinks which comprise the design, is placed against the object 8. Atemperature which is sufficient to activate the inks is then applied.This temperature will typically be around 400° F., but is selectedaccording to the sublimation properties of the inks or dyes used toprint the image onto the medium. This temperature is applied for a timesufficient to heat activate and transfer the inks. A heat transfermachine 10 may be used to accomplish the transfer of the inks from themedium to the substrate. Substantial activation, or sublimation, doesnot take place at the time of printing the image onto the medium, eventhough heat may be used to accomplish the printing of the image onto themedium, but occurs during the transfer from the medium to the substrate.

Zeolites are molecular sieves having three-dimensional networkstructures. Depending on the composition and structure, molecular sieveproducts have different cavity sizes and window opening sizes. Zeolite Ais a tetrahedral structure grouped to form a truncated octahedron with asilica or alumina tetrahedron at each point, network cavities of 11.5 Ain size, and window openings from 2.3 to 4.5 A. Zeolite A ischaracterized by the general chemical formula:

    Na.sub.12 Al.sub.12 Si.sub.12 O.sub.48 xH.sub.2 O.

Zeolite X is characterized by a tetrahedral stacking of diamondstructures, with six-membered oxygen atom rings, and window openings of9-10 A in diameter which open into the interior of the three dimensionalstructure. Zeolite X is characterized by the general chemical formula:

    Na.sub.88 Al.sub.88 Si.sub.104 O.sub.384 xH.sub.2 O.

Molecular sieves having larger window openings than zeolite A may beused. These include zeolite X, zeolite Y, ZSM-11, SAPO-5 (7.3 A×7.3 A),Mordenite (12 O windows, 6.7 A×7.0 A), VPI-5 (aluminophosphate, 10 Awindow opening 12.3 A pore size).

These molecular sieve products have relatively large surface area perunit volume and allow partial to complete entrapment of the sublimationdye molecules into their three-dimensional structure, thereby inhibitingactivation under relatively mild heat and pressure conditions providedby fusers of conventional laser printers or electrographic copiers. Highquality multi-color or full color images can be produced by usingmolecular sieve products in the toner, with no fogging of the image.Molecular sieve products improve the resistance of the toner to theadverse effects of humidity, due to their vapor absorbency properties,and further improve the surface properties of the toner.

Small particles (0.1μ to 10μ) of the molecular sieve products are usedto entrap sublimation dyes. As is detailed in the following Examples,the dye is placed into solution. The molecular sieve material is theadded. The dye molecules enter the openings of the molecular sievematerial, and are retained within the openings. The molecular sieve anddye are taken out of solution, such as by vacuum drying. The driedmixture is rinsed to eliminate excess dye which is not retained withinthe molecular sieve material, or which is not absorbed directly onto thesurface of the molecular sieve material, and is then dried again.

The molecular sieve products and sublimation dyes may be combined withvarious additives and carrier materials to produce the desired toneraccording to the invention. The resulting toner composition may comprise3 to 20% molecular sieve product by weight.

Binder polymers and/or charging control polymer materials may beincorporated into the toner. With conventional electrographic processes,a vivid color image is produced prior to or during the fixing stage ofthe printing or copying. Sufficient polyester or EVA is provided toimprove the color image. However, such materials are excellentsublimation dye receivers, and in the present invention, will retardactivation of the sublimation dyes during transfer of the image from thesubstrate medium to the second or final substrate, even when very hightemperatures are applied for long periods to effect transfer.

In the present invention, it is preferred to use binder polymers with anaverage molecular weight of 3,000-500,000 and glass transitiontemperature (T_(g)) ranges from 50°-100° C., or melting temperature(T_(m)) ranges from 60°-200° C., with good fusing performance. Examplesof such materials include homopolymer resins of soya-modified alkydresins, modified phenolic resins, soya oil and linseed oil modifiedalkyds, methylphenol-formaldehyde, xylenol-formaldehyde; homopolymer ofstyrene and substituted styrene such as polystyrene,poly(p-chlorostyene), polyvinyltoluene; and styrene copolymers such asstyrene-vinylnaphthalene copolymer, styrene-acrylonitrile copolymer,styrene-vinyl methyl ether copolymer, styrene ethyl ether copolymer,styrene vinyl methyl ketone copolymer, styrene-butadiene copolymer,styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer,styrene-maleic acid copolymer and styrene-maleate copolymer. Acceptablebinders may include terpene resins, polyamide resins, polyvinyl chlorideresins, aliphatic hydrocarbon resins, alicyclic hydrocarbon resins,aromatic petroleum resins, chlorinated paraffins and paraffin waxes.Generally, the toner composition will comprise about 50% to 90% of thebinder materials.

Since dyes and binder polymers do not give either an adequate chargelevel or rate of charging, charge control additives and/or regulatorsare added into the toner composition of preferred embodiment of thepresent invention. Either positive charge control additives or negativecontrol additives can be used as necessary to the application. Coloredor colorless quaternary ammonium salts and onium charge control agentscan be used as positive charge control additives and metal complexes,while acidified carbon blacks or fumed silica surface additives can beused as negative charge control additives. The toner may comprise 0.5%to 10% charging additives.

The present invention can be used in both single-component andtwo-component developers. Magnetite and carrier materials can be addeddepending on the specific application. In single-component applications,magnetite is added to enable the transport of the toner through thedeveloper housing, and against the latent image, under magnetic control.The addition of magnetite also offers an advantage in two-componentdevelopment, by controlling machine dirt even though the loading of suchmaterials is much smaller than the single-component applications. Thecarrier provides basically two important functions in two-componenttoner: charge generation and transport through the developer housing.The carrier can be comprised of either magnetic or nonmagneticmaterials. Typical nonmagnetic carriers include particles such as glassbeads, crystals of inorganic salts in crystal forms of sodium orpotassium chlorides, metal particles and hard resin particles, andsimilar materials. Magnetic carrier particles include ferromagneticmaterials comprised of iron, cobalt, or nickel in the form of an alloyor a mixture, and with or without film-forming resin coatings to improvethe toner triboelectrical properties of the particles.

EXAMPLE 1

5 parts Zeolite ZSM-11 (hydrogen form)¹

2 parts Intratherm Brilliant Blue P-309² as a dye material

The zeolite is ground into 20-50 micron diameter particles by, forexample, a hammer mill, and then dried, for example, in a vacuum oven at100° C. for 2 hours. The zeolite is then cooled to room temperature in adesiccator. The dye material is added into a mixture of 100 ml of1-cyclohexyl-2-pyrolidinone and 400 ml of toluene, the solution isheated to 50° C., and agitated until all dye chemical is completelydissolved. The zeolite is added to the solution and maintained at 50° C.for 2 hours under agitation. The mixture is dried under a vacuumrotating dryer, and the remaining solvent is removed in a vacuum oven at130° C./7 mm for 10 hours. A cyan dyestuff or ink composition suitablefor use in a dry toner results.

EXAMPLE 2

5 parts Zeolite 13X (sodium form)³

2 parts of Sublaprint Red 70011)⁴ as a dye material

The zeolite is ground into 20-50 micron diameter particles by, forexample, a hammer mill, and dispersed into 0.05N HCl. The ion-exchangeprocess continues for 12 hours under agitation at room temperature. Theresulting H-form zeolite is filtered and rinsed in distilled water untilthe pH value is constant.

The zeolite 13X is dried in a vacuum at 100° C. for 5 hours, and cooledto room temperature in a desiccator. The dye material is added to amixture of 50 ml of 1-cyclohexyl-2-pyrrolidinone, 100 Dimethylformamideand 300 ml of toluene, heated to 50° C. and agitated until the dye iscompletely dissolved. The zeolite is added to the solution whilecontinuing to rotate the dryer under vacuum at 130° C./7 mm for 10 hoursto the remove the remaining solvent. A magenta dyestuff or inkcomposition for use in a dry toner results.

EXAMPLE 3

50 parts Zeolite 13X (sodium form)³

19 parts Sublaprint Yellow 70004⁴ as a dye material

The yellow dyestuff or ink composion of this example is preparedaccording to the method of Example 2, and is suitable for use in a drytoner.

An example of a dry toner or ink composition for use with the method ofthe present invention is prepared as follows:

80 parts of Poly(α-methylstyrene) (T_(g) of 49° C., Softening point of141° C.)⁵

5 parts of Polywax 1000 (T_(m) of 120° C.)⁶

1 part (3-lauramidopropyl)trimethylammonium methyl sulfate

15 parts dye stuff prepared according to Example 1, 2, or 3 above.

The toner is prepared by using a melt mixing technique in a roll mill,then cooling the mixture to room temperature. The materials are groundto an average particle size of 1 to 10 microns by, for example, apulverizer in which an air jet mill is used.

Dry electrographic copier/printer toners produced by the above examplesare mixed in a ratio of one part toner of the desired color to ten partsof a carrier iron powder (EFV 250/400)⁷ to form developers in each ofthe desired colors.

A color laser printer using dry type toners, such as a QMS Magicolor, issupplied with the three colors of developers. The desired image isprinted onto ordinary paper, which acts as a substrate medium. The cyan,magenta and yellow dyes will yield a full color image as instructed bythe computer and printer, although the image which appears on thesubstrate medium is dull since the inks or dyes have not been activated.

The printer, as is chracteristic with electrographic devices, uses afuser to fuse or bind the toner after it is printed on the substrate inthe desired image by the application of heat. The heat is insufficientto activate a substantial portion of the dye due to the dye selected,the operational temperature of the fuser, and the engagement of the dyemolecules within the molecular sieve material.

The full color image is subsequently transferred from the medium to asubstrate comprising a polyester component, such as a textile, or apolymer coating, by the application of heat which is sufficient tosublimate the dye. For example, the transfer step may be accomplished inthis example by the application of heat at 400° F., and the simultaneousapplication of pressure, for twenty (20) seconds. The relatively highheat applied causes the dye molecule to be released from the molecularsieve material due to increased molecular activity from the heat,whereupon activation of the dye occurs. The dye bonds to the second orpermanent substrate to yield a full color image as desired which ispermanently bonded.

The example formulations and applications are given by way ofdemonstration, and are not exhaustive of the application of heatactivatied dyes and molecular sieves to accomplish the full colorprinting method of the present invention using dry toners andelectrographic devices.

What is claimed is:
 1. A method of printing an image by means of anelectrographic device using heat activated dyes, comprising the stepsof:a. preparing at least one ink composition comprising a heat activateddye and a molecular sieve; b. printing said ink composition by means ofan electrographic device onto a medium to form an image on said medium,wherein said printing of said ink composition by said electrographicdevice is at a temperature which is below a temperature at which asubstantial portion of said ink composition is activated; c. applyingmechanical means to said image and binding said image to said mediumwithout activating a substantial portion of said ink composition; d.removing said medium from said electrographic device; and e.transferring, at a location which is remote from said electrographicdevice said image from said medium onto a substrate on which the imageis to appear by the application of heat to said medium at a temperaturewhich is above the temperature at which said ink composition activates,so as to cause a substantial portion of said ink composition toactivate, wherein said dye bonds to said substrate and said image isdeposited onto said substrate from said medium and is bonded to saidsubstrate.
 2. A method of printing an image by means of anelectrographic device using heat activated dyes as described in claim 1,wherein at least three ink compositions are prepared and each of saidink compositions comprises a heat activated dye which is of a differentcolor than is present in each of the remaining ink compositions.
 3. Amethod of printing an image by means of an electrographic device usingheat activated dyes as described in claim 2, wherein said inkcompositions so prepared are dry compositions.
 4. A method of printingan image by means of an electrographic device using heat activated dyesas described in claim 1, wherein said ink composition so prepared is adry composition.
 5. A method of printing an image by means of anelectrographic device using heat activated dyes, comprising the stepsof:preparing at least one ink composition comprising a heat activateddye and a molecular sieve for shielding said heat activated dye; b.printing said ink composition by means of an electrographic device ontoa medium to form an image on the medium, wherein said printing of saidimage by said electrographic device is at a temperature which is below atemperature at which a substantial portion of said heat activated dyewithin said ink composition is activated; and c. transferring said imagefrom said medium onto a substrate on which the image is to appear byapplying heat to said medium at a temperature which is above thetemperature at which said ink composition activates, so as to cause asubstantial portion of said ink composition to activate, wherein saiddye bonds to said substrate and said image is deposited onto saidsubstrate from said medium.
 6. A method of printing an image by means ofan electrographic device using heat activated dyes as described in claim5, wherein at least three ink compositions are prepared and each of saidink compositions comprises a heat activated dye which is of a differentcolor than is present in each of the remaining ink compositions.
 7. Amethod of printing an image by means of an electrographic device usingheat activated dyes as described in claim 6, wherein said inkcompositions so prepared are dry compositions.
 8. A method of printingan image by means of an electrographic device using heat activated dyesas described in claim 5, wherein said ink composition so prepared is adry composition.